May 2006

Nanotechnology

New publications, experiments, and breakthroughs in nanotechnology -- and what they mean.

By TR Editors

DNA Origami
Simple synthesis could bring nanoscale design to the masses.

Source: "Folding DNA to Create Nanoscale Shapes and Patterns"
P. W. K. Rothemund
Nature 440(7082): 297-302

Results: Paul Rothemund, a Caltech computer scientist, has developed a simple technique for building nanometer-scale, two-dimensional structures of any shape or pattern from DNA. So far, he's made, among other things, smiley faces, the letters "DNA," and a map of the Western Hemisphere. These structures can also be combined to form larger shapes. Since the shapes "self-assemble" in solution, billions of them can be made at once.

Why It Matters: DNA is a versatile raw material for nanoscale structures. But past methods of using DNA as a nano building block were slow, labor intensive, and expensive, which limited their use to a handful of labs. The new technique is simple and inexpensive enough for widespread use, Rothemund says. Since a variety of molecules and nanoparticles can be linked to DNA, the technique could be a way of quickly patterning molecules as diverse as proteins and carbon nanotubes, possibly leading to minute electronic devices or "nanoarrays" for studying cells at an unprecedented level of detail.

Methods: Rothemund begins with a solution containing long strands of DNA with a known sequence. He then adds hundreds of different short "staple strands," each with a sequence designed to latch on to two or three specific sections of the long strand. As the staples connect, they pull these sections together, causing the long strand to fold into the desired shape.

Next Step: Using the technique to make electronics will require the invention of a nanoscale equivalent of the transistor. Also, since any self-assembly process is prone to error, engineers will need to develop fault-tolerant computer architectures. For biological applications, such as sensors that determine the kinds of proteins in a particular cell, researchers will need to find a reliable way to read signals transmitted by the minuscule devices. Rothemund expects that the best applications of the new technique are yet to be imagined.